What is CVE-2018-12550?

CVE-2018-12550 is a high-severity vulnerability in Eclipse Mosquitto, classified under Expected Behavior Violation. CVSS score: 8.1/10. Published 2019-03-27.

How severe is CVE-2018-12550?

High severity. CVSS v3 base score is 8.1 out of 10.

Vulnerability in Eclipse Mosquitto

CVE-2018-12550

When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use an ACL file, and that ACL file is empty, or contains only comments or blank lines, then Mosquitto will treat this as though no ACL file has been defined and use a default allow policy. The new behaviour is to have an empty ACL file mean that all access is denied, which is not a useful configuration but is not unexpected.

Published 2019-03-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.014 (71.1th percentile), scored 2026-10-19.

Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 71.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Eclipse Mosquitto
The Eclipse Foundation Mosquitto — versions 1.0, unspecified

Weakness classification (CWE)

CWE-440 — Expected Behavior Violation

References

bugs.eclipse.org/bugs/show_bug.cgi (Issue Tracking, Vendor Advisory)
lists.debian.org/debian-lts-announce/2019/10/msg00035.html (mailing-list)

Frequently asked questions

What is CVE-2018-12550?: CVE-2018-12550 is a high-severity vulnerability in Eclipse Mosquitto, classified under Expected Behavior Violation. CVSS score: 8.1/10. Published 2019-03-27.
How severe is CVE-2018-12550?: High severity. CVSS v3 base score is 8.1 out of 10.